import numpy as np

c = input()
c = c.replace(" ", "", 2)


def is_kadomatsu(s):
    li = list(s)
    rank = np.argsort(li)
    if rank[0] == 1 or rank[2] == 1:
        return True
    else:
        return False


c1 = c.replace("?", "1")
c4 = c.replace("?", "4")

ans = ""
if is_kadomatsu(c1):
    ans += "1"
if is_kadomatsu(c4):
    ans += "4"

print(ans)